Every audio product Sonos has delivered so far has worked on the assumption that you would never need anything else after you bought it, whether it's linking to a sound system you already owned or an all-in-one system that Sonos built itself, like the Play:3 or Play:5 (born as the S5). The newly released Sub, by its nature, is entirely dependent on having one of the two Play speakers, and shows the company is becoming more of a traditional audio brand with a full ecosystem.
Engadget , Sonos Sub review, Sonos Sub review
